A vehicle damper device is well known that is disposed on a power transmission path between a power transmission member coupled to a crankshaft of an engine and an output shaft to suppress transmission of torsional vibration during power transmission. One example is a damper device included in a lockup device disposed on a hydraulic power transmission device of Patent Document 1, for example. The damper device included in the lockup device of Patent Document 1 mainly includes a piston, a first coil spring, an inertia member, a second coil spring, and an output plate. The first coil spring is interposed between the piston and the output plate in a power transmittable manner and the second coil spring is interposed between the inertia member and the output plate in a power transmittable manner.
In the damper device of the lockup device of Patent Document 1, the inertia member and the second coil spring act as a dynamic damper. Therefore, if torsional resonance occurs in a drive system, vibration energy thereof is absorbed by the dynamic damper. The natural frequency of the dynamic damper is adjusted to a value substantially identical to the natural frequency of the drive system by adjusting the inertial mass of the inertia member and the stiffness of a second elastic member.